The purpose of this open-label, 2:1 randomized phase III trial is to compare the safety and efficacy of talazoparib (also known as BMN 673) versus protocol-specific physician's choice in patients who have locally advanced and/or metastatic breast cancer with germline BRCA mutations.

First-line locally advanced and/or metastatic breast cancer with no prior adjuvant chemotherapy unless the Investigator determines that one of the 4 cytotoxic chemotherapy agents in the control arm would otherwise be offered to the subject

Prior treatment with a PARP inhibitor (not including iniparib)

Not a candidate for treatment with at least 1 of the treatments of protocol-specific physician's choice (ie, capecitabine, eribulin, gemcitabine, vinorelbine)

Subjects who had objective disease progression while receiving platinum chemotherapy administered for locally advanced or metastatic disease; subjects who received low-dose platinum therapy administered in combination with radiation therapy are not excluded

Subjects who have received platinum in the adjuvant or neoadjuvant setting are eligible; however, subjects may not have relapsed within 6 months of the last dose of prior platinum therapy

Cytotoxic chemotherapy within 14 days before randomization

Radiation or anti-hormonal therapy or other targeted anticancer therapy within 14 days before randomization

HER2 positive breast cancer

Active inflammatory breast cancer

CNS metastases

Exception: Adequately treated brain metastases documented by baseline CT or MRI scan that has not progressed since previous scans and that does not require corticosteroids (except prednisone ≤ 5 mg/day or equivalent) for management of CNS symptoms. A repeat CT or MRI following the identification of CNS metastases (obtained at least 2 weeks after definitive therapy) must document adequately treated brain metastases.

Subjects with leptomeningeal carcinomatosis are not permitted

Prior malignancy except for any of the following:

Prior BRCA-associated cancer as long as there is no current evidence of the cancer

Carcinoma in situ or non-melanoma skin cancer

A cancer diagnosed and definitively treated ≥ 5 years before randomization with no subsequent evidence of recurrence